Staple gun



FIG. 1 is a perspective view showing the top side, the front side and the left-hand side of a staple gun according to the invention;

FIG. 2 is a perspective view showing the top side, the rear side and the right-hand side of the staple gun; and,

FIG. 3 is a perspective view showing the underside, the rear side and the right-hand side of the staple gun. 

The ornamental design for a staple gun, as shown. 